Treatment of paraffin hydrocarbons



Patented Mar. 25, 1941 UNITED STATES 2,236,099 TREATMENT, OF PARAFFIN HYDROCARBONS Vladimir N. Ipatiefl and Herman Pines, Chicago,

Ill., assignors to Universal Oil Products Com- 1 pany, Chicago, 111., a corporation of Delaware No Drawing. Application April 17, 1939,.

Serial No. 268,346

Claims. (01. 196-10) This application is a. continuation-in-part of my application Serial No. 35,237, filed August 8,

This inventionrelates particularly to the treata": ment of parafiinic hydrocarbons and more particularly the butanes which are normally gaseous though'in its. broadest aspect it includes the treatment of ordinary liquid paraffin hydrocarbons.

In av specificsense the invention is concerned with a process for alkylating 4 carbon atom butanes with olefins which are normally gaseous to produce saturated hydrocarbons of higher molecular weight which can be utilized as constituents of motor fuel for automobile and aeroplane engines.

There is a very large production of fixed gases in connection with the production and refining of petroleum. Large amounts of butanes occur in natural gas and well or casinghead gases and further quantities as well as normal and isobutenes and propane areproduced incidental to the cracking of the heavier portions of petroleums with the principal object of producing gasoline. Petroleum gases are as a rule utilized only asa fuel and from the standpoint of the oil refiner who is preliminarily concerned with the manufacture of gasoline and lubricating oils these gases are mainly considered as waste material, 39 so that considerable experimentation has been conducted to find methods for converting them into liquid products with practical efficiency.

The utilization of these gaseous materials has been attempted by employing straight thermal treatment without catalysts, which methods in- \volve ordinarily relatively highertemperatures and pressures than those employed in oil cracking operations and by catalytic processes which as a rule operate under less severe conditions. it] In one of its aspects the present process is a development of and an improvement in the latter type of process.

In one specific embodiment the present invention comprises the alkylation of iso-parafflns or mixtures of iso and normal parafflns with normally gaseous olefin hydrocarbons at temperatures within the approximate range of to 400 C. in the presence of catalysts comprising H generally metal halides and hydrogen halides W which are suitable for accelerating alkylation reactions.

The essential feature of the present invention is the utilization of properly chosen conditions of operation with respect to temperature, pressure, cor centration of reactants and time of contact Ill ' so that the ordinarily vigorous action of the general class of salts mentioned in catalyzing polymerization reactions among olefinic hydrocarbons is moderated so that reactions of alkylation occur rather than simple polymerization of the 5 olefins involved. In other words, selected conditions are employed at which the rate of the polymerization reactions is kept at a practical minimum while the rate of the alkylation reactions is maintained at a relatively high level so 10 that alkylation of paraifins takes place in pref.- erence to simple polymerization of the olefins involved. As a further feature of the invention the process is so conducted that a considerable molal excess of paraffin is always present in proportion to the olefins and alkylation reactions are further fostered in preference to polymerization.

An extensive series of experiments has indicated that normal paraffins are not capable of. being directly alkylated with olefins and that 20 iso-paraflins react readily. The process is therefore most readily applicable to iso-paraffins such as iso-butane or other corresponding branched chain hydrocarbons of higher molecular weight and normally liquid characteristics. In so faras isomerization reactions may take place during the treatment of normal parafiins with olefins in the presence of the preferred catalyst, alkylation has been found to occur. This tendency may be further favored in the alkylation of mixtures of iso and normal parafiins in which case the excess energy of the reaction involved in the alkylation of iso-paraffins influences the activity of normal paraflins in the mixture so that a certain degree of alkylation takes place probably through 3 the primary step of isomerization, although this mechanism is difficult to demonstrate exactly by experiment.

The present invention contemplates the alternative use of a considerable number of metal halide-hydrogen halide combinations for assisting in bringing about the desired alkylation reactions. There is no exact equivalency in the action or these composites, and the use of anyparticular one or any combination will require particular combinations of temperature, time of contact and details or operation both during the. reaction period and in the subsequent separation and fractionation of the products.

Among the metal halides which may be employed to accelerate the alkylation reactions may be mentioned aluminum chloride, zinc chloride. ferric chloride, and stannic chloride, each one of which will require specially selected temperature conditions and details of procedure depending upon their physical properties and their effect upon a particular alkylation reaction. Aluminum chloride and ferric chloride are commonly best utilizable in a substantially anhydrous condition and in conjunction with a smaller quantity of hydrogen chloride. Zinc chloride and stannic chloride may be employed either in the substantially anhydrous state or in solutions of such concentration that they are sufliciently fluid at the temperature of use. These solid salts may be employed on relatively inert and granular carrying materials to assist in their dissemination throughout a reacting mixture and assist in increasing the intimacy of contact.

The process of the invention is particularly applicable to the alkylation of iso-butane with the normally gaseous olefins and particularly with the butenes and propene although ethene can also be employed under suitably modified conditions. These alkylation reactions are of particular importance in the oil industry in connection with the cracking process, the fixed gases which ordinarily contain large quantities of 3 and 4 carbon atom hydrocarbons both oleflnic and saturated. Processes are at the present time in commercial operation which either thermally or catalytically polymerize the 3 and 4 carbon atom olefins to form liquid products suit able as hydrocarbon motor fuel but in both types of processes the parafiinic hydrocarbons in the selected fractions or mixtures are substantially unaffected so that the gasoline-forming potentialities of the gases are not completely utilized. By means of the present process the oleflns may be caused to combine to a large extent with the butanes present in such gases to produce gasoline boiling range liquids of a saturated but still of a high antiknock character so that the ultimate yield of light hydrocarbon liquids from cracked gas mixtures such as stabilizer refluxes is considerably increased.

The principles of the present invention also find application in the alkylation of paraffin hydrocarbons or their mixtures which are normally liquid. The broad temperature range mentioned as utilizable with various combinations of hydrocarbonsand various catalysts covers practically all those which are necessary for the present type of reactions. Owing to the extensive possibilities in combinations of different olefins and different parafiins which might be employed in the reactions the total range of operating conditions which the invention comprises is somewhat difiicult to state. Pressures may be employed when necessary to prevent undue losses of materials by vaporization and maintain the hydrocarbons undergoing reaction substantially in liquid phase. In general aluminum chloride is the most active of the catalytic materials proposedand in its use the lower temperatures within the range mentioned, for example. 50'

some modification depending upon the normal phase of the reacting constituents and whether batch or continuous operations are employed. In a simple type of low temperature batch operation a paraflin to be alkylated, such as, for example iso-butane is maintained at a suitably chosen temperature, usually below 20 C. when aluminum chloride is used as a catalyst, and its alykylation is effected by the gradual introduction of an olefin, such as, for example, isobutene under the surface of the liquid which may be mechanically stirred to efl'ect intimate contact between catalyst and reacting compounds and prevent subsidence of sludges which are heavier than the liquid menstruum. In another method of operation the cooled and liquid paraffin may be mixed with a liquid olefin at a suitably chosen temperature, a suitable catalyst added and the reactions of alkylation induced by a sufiiciently long contact with the catalyst chosen. Alkylation may be allowed to progress to diflerent stages of replacement. In the case of the alkylation of butanes with propene or the butenes, the best products from thestandpolnt of motor fuel usually are produced by the condensation of equimolecular quantities. After a batch treatment is completed the partially spent catalyst is allowed to settle, and the upper hydrocarbon layer is removed by decantation and subjected to fractionation for the removal of uncombined hydrocarbons as a light overhead and the recovery of an intermediate motor fuel fraction.

In continuous operation a liquid paraflin containing suspended therein the requisite amount of catalyst and maintained at a proper temperature may be pumped through a tubular treater, the desired alkylation reactions taking place during passage through the treater and the fractionation of the product accomplished in succeeding fractionating equipment. The details of continuous processes of this general character are more or less familiar to those skilled in oil refinery operations and any necessary additions to or modifications of the above general procedures will be more or less obvious. and can be made without departing fromithe general scope of the invention.

While the present process possesses particular advantages in connection with the utilization-oi the gases produced in oil cracking plants, it has a broader significance and includes generally the interaction of any olefin'and any reactive paraffin or mixture thereof at temperatures at which alkylation reactions are fostered by the preferred catalysts in preference to the simple polymerization of the olefins.

The following examples are given as illustrative of the type of results normally obtainable by the use of the present process, although it is not given with the intention of limiting the generally broad scope of the invention.

Example I 50 parts by weight of iso-butane were alkylated by 62 parts of iso-butene. The paraffin was cooled to a temperature of 30 C. and 20 parts by weight of finely divided anhydrous aluminum chloride was maintained in suspension by mechanical stirring devices. During the stirring a partially cooled stream of iso-butene was introduced along with a small quantity of hydrogen chloride. After the reaction there was a lower layer of aluminum chloride plus certain addition complexes which amounted to 30 parts by weight while the upper layer consisted of 100 partsby weight of a hydrocarbon product which was entirely parafiinic as indicated by its complete stability toward potassium permanganate solutions and nitrating mixture. This layer was water-white and 80% of it boiled below 400 F. The octane number according to the CFR motor method Was 85. I

Example [I f To illustrate the directfapplicationof the process in the improvement, in antiknock value of a gasoline, a stabilizer reflux waspassed into a paramnic gasoline at a temperature of C. in which was suspendedabout 5% by weight of anhydrous aluminum chloride, the: necessary trace of hydrogen chloride being added to the gas mixture. The stabilizer reflux consisted of approximately 15% by volume of 4 carbon atom olefins and of 4 carbon atom parafflns. After the passage of about 2000 cubic feet of stabilizer reflux (calculated on a gas basis) per barrel of gasoline and the subsequent stabilization of the gasoline to a 10 pound vapor pressure it was found that the gasolinehad increased in weight by about% and that the octane number had been increased from an original value of to 65 by the motor method. The observed increase in octane number was due principally to the alkylation of iso-butane with iso-butene.

The foregoing specification has disclosed the character and scope of the present invention and the examples have shown its practical aspects, but neither section is to be considered as unduly limiting.

We claim as our invention:

1. A. process for synthesizing hydrocarbons which comprises alkylating a parafiin with a normally gaseous olefin at a. temperature within the range of to C. in the presence of alu minum chloride and hydrogen chloride.

2. A process for synthesizing hydrocarbons which comprises alkylating an iso-paraflin with a normally gaseous olefin at a temperature within the range of 50 to +60 C.. in the presence of aluminum chloride and hydrogen chloride.

3. A process for producing hydrocarbons boiling in the gasolinerange which comprises alkyl ating iso-butane'with a normally gaseous olefin at a temperature within the range'of -50 to +60 C. in the presence of aluminum chloride and hydrogen chloride.

4. A process for synthesizing hydrocarbons which comprises alkylating a paraflin with an olefin at a temperature within the range of 200 C. in the presence of zinc chloride and hydrogen chloride.

5. A process for synthesizing hydrocarbons which comprises alkylating an iso-parafiin with an olefin at a temperature within the range of 100 to 200 C. in ;the presence of zinc chloride and hydrogen chloride.

6. A process for synthesizing hydrocarbons which comprises alkylating a paraifin with an olefin at a temperature within the range or 100 to 200 C. in the presence of ferric chloride and hydrogen chloride.

7. A process for synthesizing hydrocarbons which comprises alkylating an iso-paraffin with olefin in the presence of a metal halide catalyst .and a hydrogen halide.

11. A process for producing hydrocarbons boiling in the gasoline range which comprises alkylating isobutane with a normally gaseous olefin in the presence of a metal halide catalyst and a' hydrogen halide.

12. A process for synthesizing hydrocarbons which comprises alkylating a paramn with an olefin in the presence of aluminum chloride and hydrogen chloride.

13. A process for synthesizing hydrocarbons which comprises alkylating an isoparaflin with an olefin in the presence of' aluminum chloride and hydrogen chloride.

14. A process for synthesizing hydrocarbons which comprises alkylating isobutane with an olefin in the presence of aluminum chloride and hydrogen chloride.

15. A process for producing hydrocarbons boiling in the gasoline range which comprises alkylating isobutane with a normally gaseous olefin in the presence of aluminum chloride and hydrogen chloride. 7

. VLADIMIR N. IPA'I'IEFF'.

HERMAN PINES. 

